ASME Y14.2-2008 pdf download

ASME Y14.2-2008 pdf download.Line Conventions and Lettering.
Symmetry lines are used when representing partially drawn views and partial sections of symmetrical parts (see Fig. 3). Visible and hidden lines in symmetrical views may extend past the center line when clarity is improved. 2.9 Dimension, Extension, and Leader Lines These are solid lines used to dimension drawings as described in paras. 2.9.1 through 2.9.3.2 (see ASME Y14.5M). 2.9.1 Dimension Line. Dimension lines are used to indicate the extent and direction of dimensions, and are terminated with uniform arrowheads (see Figs. 1 and 2). Arrowheads shall be drawn within the limits of the dimension line when possible [see Fig. 8, illustration (a)]. When inadequate space is available, the dimension lines and arrowheads may be shown outside the dimen- sional limit [see Fig. 8, illustration (b)]. 2.9.2 Extension Lines. Extension lines are used to indicate the point or line on the drawing to which the dimension applies (see Figs. 1 and 2). They are also used to indicate the extension of a surface to a theoretical intersection (see Fig. 9). 2.9.3 Leader Lines. Leader lines are used to direct notes, dimensions, symbols, item numbers, or part num- bers on the drawing (see Figs. 1 and 2). A leader line should be a straight inclined line, except for a short horizontal portion extending to the center of the height of the first or last letter or digit of the note. Leader lines may consist of one or more line segments (see Fig. 10). Leaders may be drawn with a hidden line style when pointing to a hidden surface. The horizontal portion of the leader shall not underline the note, and may be omitted entirely. A vertical line may be used at the end of the leader to group information. When the vertical line is used, 6 the leader line may terminate at any point on the verti- cal line. 2.9.3.1 Terminate leaders as follows: (a) without an arrowhead or dot, when they end on a dimension line [see Fig. 10, illustration (a)] (b) with a dot 1.5 mm minimum diameter, when they end within outlines of an object [see Fig. 10, illustra- tion (b)] (c) with an arrowhead, when they end on the outline of an object [see Fig. 10, illustration (c)] (d) without a terminator for a datum target 2.9.3.2 Leader lines (a) should not cross (b) should not be excessively long (c) shall not be parallel to adjacent dimension, exten- sion, or section lines (d) shall not be drawn at small angles to terminating surfaces (e) shall not be vertical or horizontal 2.10 Cutting-Plane and Viewing-Plane Lines Cutting-plane and viewing-plane lines are used to indicate the location ofcutting planes for sectional views and the viewing position for removed views (see Figs. 1 and 2). Cutting-plane and viewing-plane lines shall be drawn to stand out clearly on the drawing. The ends of the lines are at 90 deg, and terminated by arrowheads to indicate the direction of sight for viewing (see Fig. 2 and ASME Y14.3M). Three forms of cutting-plane and viewing-plane lines are as follows: (a) evenly spaced dashes [see Fig. 1 (line 9)]. (b) alternating long dashes and pairs of short dashes. The long dashes may vary in length, depending on the size of the drawing [see Fig. 1 (line 10)]. (c) Figure 1 (line 11), same as lines 9 and 10, except the dashes between line ends are omitted.
4 LETTERING For clarity within this Standard, lettering means both letters and numerals. Paragraphs 4.1 through4.6identify the type and style of lettering for use on drawings. 4.1 Lettering Type Lettering should be single stroke gothic, opaque, and well spaced characters as shown in Figs. 13 and 14. When additions or revisions are made to a drawing, the original style of lettering shall be maintained. 4.2 Letter Style Either inclined or vertical lettering is permissible. Only one style of lettering shall be used throughout a drawing. The preferred slope for the inclined characters is approximately 68 deg from the horizontal (see Fig. 13). 4.3 Letters — Upper and Lower Case Upper case letters shall be used for all lettering on drawings unless lower case letters are required (see Figs. 13 and 14). 4.4 Letter Height The minimum letter heights for various size drawings are shown in Tables 1 and I-1. 4.5 Letter Spacing Letters in words should be spaced so the background areas between the letters are approximately equal, and words are clearly separated. The space between two numerals having a decimal point between them is to be a minimum of two-thirds the height of the lettering. The vertical space between lines of lettering shall be no more than the height of the lettering, or no less than half the height of the lettering.